Indicator tube utilizing a plurality of discharge states

ABSTRACT

An indicator tube device which contains a gas mixture and containing a plurality of pattern display cathodes and a main anode disposed adjacent the cathodes, and with one or more auxiliary electrodes mounted in the tube, and a shield plate formed with an aperture mounted between the pattern display cathodes and the auxiliary electrode such that negative glow discharge is produced on the auxiliary electrode or positive column discharge is generated in the vicinity of the aperture by controlling the amplitude and/or the polarity of the voltage applied to the auxiliary electrode.

United States Patent Inventor Kiroku Miyasalta Kawasaki, Japan Appl. No. 89,110

Filed Nov. 12, 1970 Patented Jan. 11, 1972 Assignee Okaya Denki Sangyo Kabushikikaisha Tokyo, Japan Continuation-impart of application Ser. No. 670,318, Sept. 25, 1967, now abandoned. This application Nov. 12, 1970, Ser. No. 89,1 10

INDICATOR TUBE UTILIZING A PLURALITY 01F DISCHARGE STATES 4 Claims, 6 Drawing Figs.

int. Cl 1105b 35/00 Field of Search 340/324,

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[56] References Cited UNITED STATES PATENTS 2,996,635 8/1961 Klepp et a] 313/1095 3,242,377 3/1966 Reis 315/334 3,293,493 12/1966 Johnson et a1. 315/358 OTHER REFERENCES Gaseous Conductors 1st Ed. 3rd Impr. by J. D. Cobine; Mc-

Graw-Hill Book Co., Inc.; pp. 205- 219 and 232- 239 Primary Examiner.lohn W. Caldwell Assistant Examiner-Marshall M. Curtis Attorney-Hill, Sherman, Meroni, Gross & Simpson ABSTRACT: An indicator tube device which contains a gas mixture and containing a plurality of pattern display cathodes and a main anode disposed adjacent the cathodes, and with one or more auxiliary electrodes mounted in the tube, and a shield plate formed with an aperture mounted between the pattern display cathodes and the auxiliary electrode such that negative glow discharge is produced on the auxiliary electrode or positive column discharge is generated in the vicinity of the aperture by controlling the amplitude and/or the polarity of the voltage applied to the auxiliary electrode.

PAIENIEB mu I ma sum 1 OF 2 Ia ll I N VENTOR.

[iii "016a fZg awa/fa BY W/ATTORNEYS INDICATOR TUBE UTILIZING A lPLURALITY OF DISCHARGE STATES CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-impart of application Ser. No. 670,318, filed Sept. 25, I967, now abandoned by Kiroku Miyasaka and entitled INDICATOR TUBE DEVICE.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an indicator tube and particularly to an indicator tube which includes a control device for producing an additional display with a different color than that used for a display of a desired pattern by the display cathodes.

2. Description of the Prior Art It has not been previously proposed to produce different colors of desired patterns in a single indicator tube. In indicators it is desirable to indicate decimals in a color different than that used for number displays but this has not been possible with conventional types of indicator tubes.

SUMMARY OF THE INVENTION The primary object of this invention is to provide an improved indicator tube.

Another object of this invention is to provide an indicator tube device which displays an additional pattern in a color different from that used for a main pattern.

A further object of this invention is to provide an indicator tube device which displays a decimal in a color different from that used for number display.

A still further object of this invention is to provide an indicator tube in which a pattern can readily be displayed in a color similar to or different from that for a main pattern on or near an auxiliary electrode by controlling the amplitude and/or the polarity of voltages applied thereto.

Other objects, features and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic front view of an indicator tube of this invention, illustrating by way of example an electrode structure employed therein:

FIG. 2 is a connection diagram of switching means for changing the direction of a discharging current passing through an auxiliary electrode of the indicator tube;

FIG. 3 is a connection diagram illustrating one example of an indicator tube control device of this invention;

FIG. 4 is a connection diagram illustrating another example of the control device;

FIG. 5 is a connection diagram illustrating another example of the electrode structure and an external circuit of the indicator tube device of this invention; and

FIG. 6 is a connection diagram illustrating one example of the external circuit shown in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In recent years, the demand for indicator tubes for use in counters and electronic computers has grown due to their high speed and reliability. They are also inexpensive and have long life. Such indicator tubes are of particular utility when used for displaying numbers containing many units. The tubes may be made very small. In prior art tubes, when displaying a number of many units, it is difficult to determine where the decimal point is located. The indicator tube of this invention, free from the drawbacks of the prior art, is applicable to the display of numerals and signs such as decimals.

An indicator tube control device of this invention allows the production of negative glow discharge, for example, in reddish orange or positive column discharge in bluish green at desired locations in the indicator tube. With the use of this control device, decimal and unit indications can be distinctly produced in different colors, if desired.

In FIG. 1 reference character T designates generally an in dicator tube, which has sealed a mixture of gases consisting of, for example, 99.3 percent by weight of neon gas and 0.7 percent by weight of argon gas, together with a sufiicient amount of mercury for yielding saturated vapor pressure at working temperatures. The neon gas may vary from 99 to 99.5 percent and the argon gas may vary from I to 0.5 percent. The pressure of the mixture gas is about 25 to 40 mm. mercury, preferably approximately 30 mm. of mercury. The indicator tube T contains a plurality of pattern display cathodes 2 in the shape, for example, of the numeral 0 to 9.

Numerals 6 and 7 are illustrated and the cathodes are insulatingly secured to a support structure. A main anode l insulatingly supports the cathodes 2 by upper and lower support rods 7. The front portion of the main anode l facing the pattern display cathodes 2 is constructed of fine wires la spaced at suitable intervals. Reference numeral 5 indicates mica plates for assembling and supporting the cathodes 2 and anode 1 within the glass envelope 8. v

In accordance with this invention the indicator tube T contains the pattern display cathodes 2, the main electrode 1, an auxiliary electrode 3 and a shield plate 4. The plate 4 has an aperture 6 that may be 2-3 mm. in diameter, for example. Plate 4 is mounted between the pattern display cathodes 2 and the auxiliary electrode 3.

The indicator tube T including the auxiliary electrode 3, operates with a circuit C including a switching means. This will be described later. The switching means C changes the direction of the discharge current passing through the auxiliary electrode so that positive column discharge is produced in bluish-green color in the vicinity of the auxiliary electrode 3 when the discharging current flows from the auxiliary electrode 3 to the pattern display cathodes 2 and negative glow discharge is generated in reddish-orange color on the auxiliary electrode 3 when the discharging current flows from the main anode 1 to the auxiliary electrode 3.

FIG. 2 illustrates the connection of the switching means C. As shown in FIG. 2, a terminal 9 is connected to a positive power source terminal 16 through a suitable resistor 18. Terminal 9 is connected to the main anode l. A terminal 15 is connected to the auxiliary electrode 3. A terminal 10 is connected to the negative power source terminal 17 and may be connected to a selected one of the pattern display cathodes 2 by a switch S2.

Resistor 11 is connected between terminal 16 and terminal 12 which may be engaged by contact 14 of switch S1. Contact 14 is connected to terminal 15.Resistors 11 and 18 are stabilizing resistors for maintaining discharging currents from the main anode 1 to a selected one of the pattern display cathodes 2 and from the auxiliary electrode 3 to a selected one of the pattern display cathodes 2, respectively. Contact 13 of switch S1 is connected to terminal 17. By switching the movable contact 14 of the changeover switch S1 to the stationary contact 12, the auxiliary electrode 3 is connected through the resistor 11 to the positive power source terminal 16 so that a discharging current flows from the auxiliary electrode 3 to a selected one of the pattern display cathodes 2 through the aperture 6 formed in the shield plate 4. It has been found that when the 'aperture 6 is about 2 to 3 mm. in size that positive column discharge is produced near the aperture 6 or the auxiliary electrode 3, a bluish-green color is produced due to discharge of the mercury vapor contained in the gas sealed in the tube T.

When the movable contact 14 of the switch S1 is moved to engage the stationary contact 13, the auxiliary electrode 3 is connected to the negative power source terminal 17 an a discharging current flows from the positive power source terminal 16 to the auxiliary electrode 3 through the resistor 18 and the main anode 1. In this case the auxiliary electrode 3 is covered with a reddish-orange colored negative glow discharge which is peculiar to the neon gas sealed in the tube T. Also the selected one of the pattern display cathodes 2 is covered with a reddish-orange colored discharge.

Thus, bluish-green or reddish-orange colors can be produced near the auxiliary electrode 3 by switching the movable contact 14 of the switch S1 to the positive or negative side of the power source to feed the current from or to the auxiliary electrode 3. As in the prior art the numeral or mark electrodes of the pattern display cathodes 2 are selectively corrected by means of switch S2. In FIG. 2 similar elements to those in FIG. 1 are identified by similar reference numerals.

FIG. 3 schematically illustrates one example embodying the principles of this invention in which a potentiometer 19 is mounted between terminal 17 and resistor 11. A slide contact of the potentiometer is connected to terminal and allows the voltage on electrode 3 to be varied from that on terminal 17 to a more positive voltage. Similar elements to those in FIG. 2 are indicated by the same reference numerals and a detailed description of the common structure will not be repeated.

FIG. 4 illustrates another example of the indicator tube device of this invention. Reference characters TRl and TR2 designate switching transistors and have their emitters connected to terminal 17. A photoconductive device 21 such as, for example, a cadmium sulfide cell whose resistance value lowers when subjected to light, is connected to electrode 3 and collector of transistor TRl. A neon discharge tube 24 is mounted for applying light to the photoconductive device 21. The neon discharge tube 24 is connected in series to a stabilizing resistor 22 and to the collector of transistor TR2. A resistor 25 is connected between the collector of the transistor TR2 and terminal 16. When the photoconductive device 21 receives light from the neon discharge tube 24, its resistance value lowers, and hence the composite resistance value, composed of the resistance value of the photoconductive device 21 and resistor connected in series therewith, can be made substantially equal to that of the resistor 11 of FIGS. 2 and 3.

Reference numeral 23 designates a container, shown in dotted line, which shields the photoconductive member 21 and the neon discharge tube 24 from light outside the container. In FIG. 4, elements similar to those in FIGS. 1, 2 and 3 are identified by similar reference numerals and the detailed description of the common elements will not be repeated.

When a positive voltage is applied to an input terminal 26 connected to a base of the switching transistor TRl, the transistor TRl becomes conductive and this causes the auxiliary electrode 3 to have a voltage substantially equal to the negative power source terminal 17. A circuit is then completed from positive power source terminals 16 through the resistor 18, the main anode 1 and the auxiliary electrode 3 to the negative power source terminal 17. As a result, a discharging current flows from the main anode 1 to the auxiliary electrode 3 and produces a reddish-orange color on the auxiliary electrode 3.

When a positive voltage is applied to an input terminal 27 connected to the base of the switching transistor TR2 it will conduct. At the same time switching transistor TRl is rendered inoperative. The neon discharge tube 24 emits light to lower the resistance value of the photo conductive device 21. A circuit is completed from the positive power source terminal 16 through the resistor 20, the photoconductive member 21, the auxiliary electrode 3, through the aperture 6, to a selected one of the pattern display cathodes 2 and to the negative power source terminal 17. This causes current to flow from the auxiliary electrode 3 to the selected pattern display cathode 2 through the aperture 6 thus producing a bluishgreen color in the neighborhood of the auxiliary electrode 3. It is seen that the transistors and photo device 21 and neon 24 function similar to the switching structures of FIG. 1 and 2.

FIG. 5 reference numerals 0 to 9 and a reference character d indicate cathodes for displaying patterns, for instance, the numerals 0 to 9 and a decimal point. A main anode 100 is disposed opposite the pattern display cathodes 0 to 9. An auxiliary anode 110 is mounted opposite the decimal point display cathode d. The pattern display cathodes 0 to 9 and d are respectively connected to stationary contacts 0 to 9 of selecting means S having a movable contact S and one terminal d of a switch S11. Selecting means S and switch S11 are connected to negative power source tenninal 180. The main anode and the auxiliary anode are both connected to a positive power source terminal 170. Anode 100 is connected through a stabilizing resistor 140 for maintaining a discharge of a predetermined value. Anode 110 is connected to terminal 170 through a resistor 150 which might have a value ofseveral megohms.

In the indicator tube of FIG. 5, the display of any desired one of the numerals 0 to 9 is accomplished by engagement of the movable contact m of the selecting means S with a selected one of the stationary contacts 0 to 9'. This connects negative terminal 180 to the selected pattern display cathodes 0 to 9. The decimal point is displayed if desired by closing the switch S11 to connect cathode d to terminal 180.

A shield plate 130 having formed an aperture is mounted between the pattern display cathodes 0 to 9 and the auxiliary anode 110. The shield plate may be formed integrally with the main anode 100 or may be formed separately of an insulating material such as mica or the like. The size of the aperture 120 may be 23 mm. if desired. The auxiliary anode 110 is connected to the positive power source terminal 170 through a parallel circuit of a resistor and a resistor of, for example, several 10 kilohms connected in series to a switch S20.

It has been found in the use of this indicator tube that during display of a numeral by one of the pattern display cathodes the closing of the switch S20 causes discharge between the auxiliary anode 110 and the pattern display cathode through the aperture 120 of the shield plate 130 and positive column discharge is produced in the vicinity of the aperture 120 having a color different from that of the negative glow discharge of the pattern display cathode. The gas mixture sealed in the indicator tube consists largely of neon gas and small amounts of argon gas and mercury vapor. The color emitted by the positive column discharge is bluish green which is chiefly the spectrum of mercury vapor discharge, and can be easily distinguished from the reddish-orange color of the negative glow discharge of neon gas emitted by the pattern display cathode. With the positive column discharge produced, unit indication of, for instance, every three units can be accomplished as desired. This discharge may be produced under the right-hand side of the pattern display cathodes, for example.

FIG. 6 illustrates one example of an external circuit that may be used with the device shown in FIG. 5. A switching transistor TRl performs the same function as the switch S1] and similar parts to those in FIG. 5 are identified by the similar reference numerals. Reference numeral 200 designates a photoconductive device such, for example, as a cadmium sulfide cell whose resistance value lowers when exposed to light. A light source 210, for example, a neon discharge tube excites the photoconductive device 200. Device 200 is connected between terminal and anode 110. Tube 210 is connected in series with resistor 220 to terminal 170 and through transistor TR2 to terminal 180.

Upon application of, for example, a positive voltage to an input terminal connected to the base of switching transistor TR2, the neon discharge tube 210 starts discharge and emits light and the resistance value of the photoconductive member 200 exposed to the light lowers from several megohms to several 10 kilohms. This causes the circuit to function in the same manner as when switch 20 is closed in FIG. 5.

A box 230 shields the photoconductive device 20 and the neon discharge tube 21 from unnecessary light from the outside.

The starting voltage for the positive column discharge can vary 20 or more volts depending on the shapes of the pattern display cathodes and their relative arrangement relative to the auxiliary anode 110. In order to eliminate the irregularity of the starting voltage for the positive column discharge and hence obtain substantially a constant starting voltage, a discharge is instantaneously produced between the auxiliary anode 110 and the decimal point display cathode dand ionizes the sealed gas in the vicinity of the aperture 120. It has been found that this causes the generation of positive column discharge between a selected one of the pattern display cathodes 2 and the auxiliary anode 110 through the aperture 120 with substantially a constant starting voltage irrespective of the shape and relative arrangement of the display cathodes to the auxiliary anode 110.

The circuit for producing the positive column discharge between the auxiliary anode 110 and the selected one of the pattern display cathodes to 9 and the instantaneous discharge between the auxiliary anode 110 and the decimal point display cathode d may comprise a switching transistor TR2, a capacitor 260 and resistors 240 and 250. Upon application of a positive voltage to an input terminal 190 connected to the base of the switching transistor TR2 to cause it to conduct, the neon discharge tube 210 emits light and the capacitor 260 connected between the collector of the switching transistor TR2 and the decimal point display cathode d is charged through the resistor 240. While the capacitor 260 is charged, the potential of the decimal point display cathode d becomes substantially equal so that of the negative power source terminal 180 due to voltage drop by the resistor 240, so that discharge can be produced between the auxiliary anode 110 and the decimal point display cathode d for a time corresponding to that for charging of the capacitor 260. The charging time depends on the values of the resistor 240 and the capacitor 260. The resistors 250 and 240 discharge the capacitor 260. This ensures that the decimal point display cathode d serves as a cathode for starting the positive column discharge and that the positive column discharge for unit indication can be produced in the neighborhood of the aperture 120 with substantially a constant discharge starting voltage independently of the particular shapes of the pattern display cathodes.

In a particular embodiment constructed according to this invention, the following dimensions of the electrodes and the spacings were utilized.

The spacing between adjacent cathode elements 2 was 0.7 mm. The spacing between the last cathode element and the shield 4 was 2.4 mm. The diameter of the opening 6 was 2 to 3 mm. (if the opening were circular); or, 2 to 3 mm. on each side if the opening were square shaped. The spacing between the shield 4 and the auxiliary electrode 3 was 1.8 mm. The spacing between the anodes 1 and the cathodes 2 was 0.7 mm. The overall dimensions of the cathode 2 was about l2 7.5 mm. The overall dimensions of the anode 1 was about 10.4X3 mm. The voltage between the terminals 16 and 17 was 170 volts. The value of the resistor 11 was 50 kilohms; the value of the resistor 18 was 15 kilohms; and, the value of the resistor 19 was 500 kilohms.

In FIG. 4, the value of the resistor 18 was 15 kilohms; the resistor 20, 50 kilohms; resistor 22, 250 kilohms; and, resistor 25 was I megohm.

In FIG. 5, the resistor 140 was 15 kilohms; the resistor 150 was kilohms; and, the resistor 160 was 50 kilohms.

In FIG. 6, the resistor 140 was kilohms; the resistor 240 was 1 megohm; and, the resistor 250 was I megohm. The value of the capacitor 260 in FIG. 6 was 100 picofarads.

The voltages between the terminals 16 and 17 in FIG. 4 was 170 volts. The voltage between the terminals 170 and 180 in FIG. 5 was volts; and, the voltage between the terminals 170 and in FIG. 6 was I70 volts.

It was also discovered that a mixture of gas in the range between 5 to 100 mm. of mercury may be utilized in the invention.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

Iclaim; 1. An indicator tube comprising a plurality of pattern display cathodes, a main anode disposed opposite thereto, an auxiliary electrode, a shield plate interposed between the pattern display cathodes and the auxiliary electrode, said shield plate having an aperture for determining a distance between said auxiliary electrode and said pattern display cathodes to produce a positive column glow near said auxiliary electrode when supplied with positive voltage, switching means inserted between said auxiliary electrode and power source supplying voltage to said main anode and pattern display cathodes for selectively supplying positive and negative voltages to said auxiliary electrode and, several kinds of gases, each emitting is inherent color light in the indicator tube, whereby when positive voltage is applied to said auxiliary electrode, discharge oc curs between said auxiliary electrode and one of said pattern display cathodes and also discharge between said pattern display cathode and said main anode to show said auxiliary electrode with positive column discharge color and when negative voltage is applied to said auxiliary electrode negative glow discharge is generated between said auxiliary electrode and said main anode and also between said anode and one of said pattern display cathode electrodes to show said auxiliary electrode with negative glow color.

2. An indicator tube as claimed in claim 1, wherein, said switching means consists of a movable contact and two stationary contacts, one end of said movable contact being connected to said auxiliary electrode, one of said two stationary contacts being connected to the positive side of said power source through a resistor, and the other of said two stationary contacts being connected to a negative side of said power source.

3. An indicator tube as claimed in claim 1, wherein said switching means consists of a resistor inserted between positive and negative sides of .said power source and a slide contact, one end of which is connected to said auxiliary electrode and the other end of which slidably contacts said resistor.

4. An indicator tube as claimed in claim 1, wherein said switching means consists of first and second transistors inserted in parallel with each other between positive and negative sides of said power source, a photoconductive element connected between said positive side of said power source and said first transistor, and discharge tube inserted between said positive side of said power source and said second transistor nonconductive, said discharge tube emits light to lower the resistance of said photoconductive element so as to apply a positive voltage to said auxiliary electrode and when said first transistor is conductive and said second transistor is nonconductive, said auxiliary electrode is supplied with negative voltage. 

1. An indicator tube comprising a plurality of pattern display cathodes, a main anode disposed opposite thereto, an auxiliary electrode, a shield plate interposed between the pattern display cathodes and the auxiliary electrode, said shield plate having an aperture for determining a distance between said auxiliary electrode and said pattern display cathodes to produce a positive column glow near said auxiliary electrode when supplied with positive voltage, switching means inserted between said auxiliary electrode and power source supplying voltage to said main anode and pattern display cathodes for selectively supplying positive and negative voltages to said auxiliary electrode and, several kinds of gases, each emitting is inherent color light in the indicator tube, whereby when positive voltage is applied to said auxiliary electrode, discharge occurs between said auxiliary electrode and one of said pattern display cathodes and also discharge between said pattern display cathode and said main anode to show said auxiliary electrode with positive column discharge color and when negative voltage is applied to said auxiliary electrode negative glow discharge is generated between said auxiliary electrode and said main anode and also between said anode and one of said pattern display cathode electrodes to show said auxiliary electrode with negative glow color.
 2. An indicator tube as claimed in claim 1, wherein, said switching means consists of a movable contact and two stationary contacts, one end of said movable contact being connected to said auxiliary electrode, one of said two stationary contacts being connected to the positive side of said pOwer source through a resistor, and the other of said two stationary contacts being connected to a negative side of said power source.
 3. An indicator tube as claimed in claim 1, wherein said switching means consists of a resistor inserted between positive and negative sides of said power source and a slide contact, one end of which is connected to said auxiliary electrode and the other end of which slidably contacts said resistor.
 4. An indicator tube as claimed in claim 1, wherein said switching means consists of first and second transistors inserted in parallel with each other between positive and negative sides of said power source, a photoconductive element connected between said positive side of said power source and said first transistor, and discharge tube inserted between said positive side of said power source and said second transistor nonconductive, said discharge tube emits light to lower the resistance of said photoconductive element so as to apply a positive voltage to said auxiliary electrode and when said first transistor is conductive and said second transistor is nonconductive, said auxiliary electrode is supplied with negative voltage. 